Unable to Repair or Replace Under Warranty

I bought two 7” Telefunken tablets from Game on 10 June 2017, they both carried a 1 year warranty. I kept the boxes for a couple of months and finally threw them out. Towards the end of the year both of them failed with the same fault and I took them in for repair on 18 December 2017. Game Fourways has refused to repair them, they say they will refund me, but only if I return the boxes which I no longer have. I can find no clause in their terms and conditions that state I need to keep the boxes for the duration of the warranty, and have no desire to be refunded, I simply want them fixed, or replaced if they are unrepairable!